This core will provide each of the projects with high quality tissue section, histochemistry, immunochemistry, and in situ hybridization for the in vivo analysis of pancreatic islet functions under various conditions of transplantation or genetic manipulation. The core will provide paraffin, cryostat blocks, and tissue sections for each of the projects, perform histochemical assays and Hematoxylin and Eosin counter staining, as well as carry out immunofluorescence and horseradish peroxidase-based immunodetection on paraffin embedded and cryo-preserved tissue sections. The reproducibility and standardization of these techniques are extremely important to compare transplanted or transgenic animals to controlled littermates. A similar histology core has just been set up for the Gene Therapy Program here at he University of Chicago under the directorship of Dr. Jeffrey Leiden, with whom several of the investigators work closely. It is anticipated that the increased need for tissue fixation, embedding, sectioning, and staining will make an expansion of the currently existing core facilities available. The core will also provide each of the projects with purified islets for their studies as needed. The core will be directed by Dr. Yijun Zeng, who has extensive experience in isolation and manipulation of pancreata as well as islet cell purification. In addition, the core will be staffed by a senior histology technician with experience in light microscopy, immunohistochemistry, and in situ hybridization. A dedicated technician is needed because of the expected large number of tissue samples that will be examined in each of the projects within the program.